Coarse wavelength division multiplexing (CWDM) is a technology that multiplexes multiple optical signals on a single optical fiber strand by using different wavelengths of laser light to carry different signals. There are two conventional CWDM systems. One conventional CWDM system is formed by single wavelength optical communication modules using an external multiplexer/demultiplexer (MUX/DEMUX). The other conventional CWDM system realizes zigzag optical path actions of the MUX/DEMUX using injection molded plastic optical devices and thin film filters. Such conventional techniques provide low cost and low power consumption. However, there are some issues with these conventional techniques.
FIG. 1 is a diagram showing a conventional MUX/DEMUX system 100 having a “zigzag” optical path. In MUX/DEMUX systems 100 having the zigzag optical path, light from an optical source providing multiple wavelengths enters into an optical input port 102. Subsequently, the wavelengths are separated to each output port in optical module 101 by wavelength to realize de-multiplexing. Because the de-multiplexing process is reversible, four or more light beams having different wavelengths may be combined into one output light beam in the multiplexing process.
FIG. 2 is a diagram showing a conventional MUX/DEMUX component 200. FIG. 3 is a diagram showing the internal optical path 215 of the component 200 of FIG. 2. Generally, the optical module 201 implements multiplexing/de-multiplexing using the zigzag optical path 215. The conventional MUX/DEMUX system 200 may realize a smaller size, lower cost, and easier insertion and/or extraction of the optical fiber in comparison with system 100 of FIG. 1.
FIG. 4 shows a layout of a printed circuit board (PCB) 209 having an electrical circuit 211 adapted for relatively long conventional plastic optical devices. Typically, relatively long electrical circuits negatively affect the transmission performance of high speed digital signals.
One issue with the conventional MUX/DEMUX system(s) shown in FIGS. 2 and 3 is that a lens array having an arrangement parallel with incident light can affect the transmission performance of high speed digital electrical signals at the back-end of a fiber-optic communication device. Also, during assembly of a plastic optical communication device, the accumulated tolerances of positioning of various devices such as the collimator and the MUX/DEMUX system can prevent collimated light beams from the collimator being aligned properly with lenses in the plastic optical device. As a result, conventional MUX/DEMUX systems may have a relatively low yield.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.